1. Field of the Invention
The present invention relates to a cleaning sheet for fixating rotational member, and an image forming apparatus having a fixating rotational member.
2. Related Background Art
In image forming apparatus such as copying apparatuses, laser beam printers and magnestylus printers, it is widely practised to form an unfixated toner image on a support material, and thereafter effect fixation by a fixating rotational member, particularly, a pair of rotational members.
In order to prevent toner and paper powder adhering to the fixating rotational member(s) from spreading to the support material to deteriorate the quality of image, felt, a web or the like is brought into contact with the fixating rotational member(s) to thereby clean the latter.
An example of such a fixating device is shown in FIG. 8 of the accompanying drawings.
The reference numeral 1 designates a fixating roller which comprises a mandrel 12 of aluminum, iron or like material and a resin layer 13 of good parting property such as PFA or PTFE provided on the mandrel 12 and the interior of which may be heated by a heater H. The surface temperature of the fixating roller 1 is detected by a temperature detecting element 19, and is controlled to a predetermined temperature by turning on or off the heater H by a temperature control circuit (not shown).
On the other hand, the reference numeral 2 denotes a pressing roller which comprises a metallic mandrel 21 of iron, stainless steel or the like and an elastic material layer 22 of silicone rubber, fluorine rubber or the like having a heat resisting property and a good parting property and formed on the metallic mandrel 21.
A recording material P carrying a toner image T thereon is directed to between the fixating roller 1 and the pressing roller 2 by an entrance guide 23, and is heated and pressed, whereby the image is fixated. Thereafter, the recording material P is peeled from the fixating roller 1 by a separating pawl 10.
The reference numeral 18 designates cleaning felt which comprises a felt material such as Normex (the registered trademark of Du Pont, Inc.) impregnated with a parting agent such as silicon oil and serves to remove toner and paper powder adhering to the surface layer of the fixating roller 1.
In recent years, however, as the tendency of the apparatus toward compactness and lower cost has progressed, the desire to eliminate the cleaning device has become stronger.
For this reason, efforts have been made to improve the parting (mold releasing) property of the surface of the fixating rotational member and overcome the electrostatic problem, but it has been impossible to keep a good quality of image for a long period of time.
Particularly, as, regards the pair of rotational members, the stains on the rotational member which does not contact with the unfixated toner image have been serious and the problem of the back of the support material becoming stained has occurred.